First Author:   Yi Jin The University of Kansas yjin@ku.edu   Department of Economics, The University of Kansas Lawrence, 66045, U.S.A.   1-785-8642848(Phone) 1-785-8642848(Fax) http://people.ku.edu/~yjin Second Author: Zhixiong Zeng Peking University zxzeng@ccer.pku.edu.cn   China Center for Economic Research, Peking University , 100871, China   86-10-62767507(Phone) 86-10-62751474(Fax) http://faculty.ccer.edu.cn/zxzeng/